1. Field of the Invention
The present invention relates to a heat exchanger suitable for use in automobiles, and more particularly, to an improved structure for the header cap portion and vicinity of each end portion of the header pipes of a multi-flow type heat exchanger.
2. Description of the Related Art
A multi-flow type heat exchanger, for example, used as a condenser or as an evaporator for an air conditioner in automobiles, typically comprises a pair of header pipes, a plurality of heat transfer tubes interconnecting the pair of header pipes, and fins disposed between the heat transfer tubes. The members forming the heat exchanger are first assembled, and then the assembly is integrally brazed in a furnace to form a heat exchanger.
An example of such a heat exchanger is shown in FIG. 6. During the heating phase of the brazing process, header pipe 101 may rotate at of its proper position due to an external force, such as gravity or vibration. In such a situation, inlet or outlet pipe 102, or attachment support 103 may also shift from a proper position as shown in FIG. 7, making it difficult to form a heat exchanger having a desired shape. Moreover, a connecting portion of heat transfer tube 104 and header pipe 101 may shift, which may result in an increased possibility that the heat exchanger will leak.
Further, although the heat exchanger core prepared as an assembly is secured by a jig 105 during the brazing process, fins (not shown) or heat transfer tubes 104 may become deformed or may shift due to an excessive fastening force applied by jig 105, or by a difference in thermal expansion between the heat exchanger core and jig 105. In particular, as shown in FIG. 8 (described in Japanese Utility Model Laid-Open SHO 64-46680), an end portion of side fin 113, which is disposed on the outer surface of the outermost heat transfer tube 112a of a plurality of heat transfer tubes 112 connected to header pipe 111, may positionally shift, deform or improperly connect despite the presence of side plate 114. This may result in problems as shown in FIGS. 9A and 9B. FIG. 9A shows an example in which the end portion of side fin 113 has shifted out of a proper position to a position below the proper position. FIG. 9B shows an example in which side fin 113 and side plate 114 have shifted together from a proper position.
In order to prevent such positional shifts, a structure is proposed in JP-A-HEI 7-120190 wherein respective plate portions are provided to a side member (corresponding to a side plate of the present invention) and a header cap, and the plate portions are brazed to each other in an abutted condition.
However, although the positional shift between a header pipe and a side plate may be prevented, to some extent by such a proposal, it is still not satisfactory. In particular, the prevention of the positional shift of a side fin is still insufficient.